Thread-cutting mechanism for circular-knitting machines

ABSTRACT

A ring rotating in synchronism with the needle cylinder has a cutting edge cooperating with a counterknife vibrated radially of the ring by cooperating spring and cam means. A thread is held for cutting between a rib on the ring and a shoe or disc engageable with such rib.

United States Patent Boy et a]. 1 Mar. 14, 1972 [54] THREAD-CUTTING MECHANISM FOR [56] References Cited CIRCULAR-KNITTING MACHINES UNITED STATES PATIENTS [72] Inventors: Peter Boy; Heinz Kiihler, both of Ingolr 13,443 12/1953 61 3| 66/145 R stadl; Heinz Lucke Rheine of Ger- Kaese many 3,345,834 10/1967 Parthum 66/145 S 3,396,559 8/1963 Lonati ..66 I34 I Assignw sfhubm & Sail" Mmhinenfabrik 3,488,679 1/1970 Boy ..66/I34 tiengesellschait, Ingolstadt, Germany Filed: g 1970 FOREIGN PATENTS OR APPLICATIONS 685,501 4/1964 Canada ..66/l45 S APPL @567 971,730 10/1964 Great Britain dated Application Data 660,125 1/1964 Italy 664,030 5/1964 Italy ..66/l45 R [63] Continuation of Ser. No. 704,958, Feb. 12, 1968,

abandoned- Primary Examiner-Robert R. Mackey AttorneyRobert W. Beach [30] Foreign Application Priority Data Feb. 11, 1967 Germany ..sh 40219 [571 ABSTRACT A ring rotating in synchronism with the needle cylinder has a [52] US. Cl ..66/ 134, 66/140 R, 66/145 R cutting edge cooperating with a counterknife vibrated radiauy [51] Int. Cl. ..D04b 15/61 f the ring by cooperating Spring and cam means A thread is [58] Field of Search .r

....66/l34, I40, 140 S, 145, 145 S Maw:

held for cutting between a rib on the ring and a shoe or disc engageable with such rib.

12 Claims, 8 Drawing Figureg Patented March M, Q1:

3 Sheets-Sheet f3 0 m B m? m P A T TOFNE Y Pmmed March 1%, 197

5 Sheets-Sheet 1'.

INVENTORS PE TEI? B0) mechanism which is simple and economical to construct and install.

It is a further object to provide such mechanism which is compact and which can be used without substantial modification of conventional knitting apparatus.

FIG. 1 is a side elevation of cutting mechanism according to the present invention with parts broken away and parts in section.

FIG. 2 is a top perspective of such cutting mechanism with parts broken away.

FIG. 3 is an enlarged fragmentary top perspective of a detail of somewhat modified cutting mechanism.

FIG. 4 is a fragmentary section through an alternate form of tensioning mechanism for the cutting device.

FIG. 5 is a top perspective of a modified form of knifevibrating apparatus for the cutting device.

FIG. 6 is a fragmentary vertical section through still a dif ferent modification of the cutting and vibrating mechanism;

FIG. 7 is a top plan of the mechanism shown in FIG. 6; and

FIG. 8 is an enlarged view of the portion of the counterknife indicated by dash lines in FIG. 7.

The invention is shown in connection with a circular knitting machine of the type suitable for knitting hosiery. The cutting mechanism is provided to cut thread during the continuous knitting process, such as during the exchange of thread of different denier between a stocking welt and the stocking body, or to cut the ends of interknitted reinforcing threads at the edge of an integral reinforcing section in the heel or toe of a stocking.

A disk 1 carrying sinkers 5 is rotated by shaft 4 in synchronism with a needle cylinder carrying latch needles 18. A cover plate 6 for the disk is mounted stationarily by a collar 60 on the lower portion of a bearing sleeve 30 for shaft 4. Such cover plate carries conventional thread guides 14 and 15. A pair of thread supply systems I and I] include thread guides 16 and 17 for threads FI and F2 and thread guides 16 and 17' for threads F3 and F4, respectively.

A ring knife 2 is mounted on lugs 3 of disk 1 for conjoint rotation with such disk. The ring knife may have a smooth cutting edge 21 as shown in FIG. 1 or a toothed cutting edge 27 as shown in FIG. 3. A guide ring 7 mounted on the under side of cover plate 6 prevents radial displacement of the ring knife. Rib 22 on the ring knife encircles and extends above stationary cover plate 6 to hold thread drawn across it out of engagement with such cover plate.

A bracket 9 mounted on cover disk 6 by threaded post 62 carries a holder 13 for counterknife 11. A spring 12 biases the knife 11 downward toward ring knife cutting edge 21. The knife holder 13 is formed as a bellcrank pivotable about a pin extending through spring 12. The counterknife is suspended from one end of the bellcrank and the opposite end of the bellcrank has a depending heel which constitutes a cam follower 130 engageable with cam means in the form of a serrated surface 23 on a small arc of the outer face of annular rib 22, the grooves of which surface are indented from the general cir- 'cumference of the rib surface in which they are formed. A tension spring 8 biases the cam follower 130 toward the serrated surface 23, so that the cam follower and serrated surface cooperate to vibrate the bellcrank and thereby swing the counterknife end of the bellcrank into cooperation with the ring cutting edge. A nonrotative shoe 25 mounted on cover plate 6 is biased against and rides on the upper edge of rib 22 as such rib rotates, but the shoe can be lifted intermittently out of engagement with the rib by a cam 24 carried on such rib to release the severed end of a thread.

The operation of the thread-cutting and tensioning mechanism, best shown in FIGS. 2 and 3, is described, for example, in connection with cutting the reinforcing threads at the edge of a stocking heel. While the two basic threads F1 and F3 are used to continue knitting of the foot portion of the stocking, reinforcing threads F2 and F4 must be cut. As seen in FIG. 3, thread F2 has been cut and its free end is retained in the bottom of suction tube 37 mounted on cover plate 6. The last needle 18 operable to engage the reinforcing thread F4, in completing the knitting of a particular stretch of such reinforcing thread, while the needle cylinder turns through a substantial angle, will pull such thread into a chordal position extending across rib 22 until the thread is engaged by the inclined end of shoe 25. As needle 18 continues to advance past the shoe, it wedges the thread tightly under such shoe so that the stretch of thread between the shoe and needle 18 is tensioned when such stretch extending across the ring knife cutting edge is pulled under counterknife 11. Also, because the shoe deters further movement of the thread stretch transversely of its length toward mounting bracket 9, the thread is rolled by rotation of rib 22 into a substantially radial position when it engages the counterknife.

As the counterknife is vibrated by engagement of cam follower 130 with the serrations of surface 23, the thread will be shared by coaction of the cooperating counterknife I1 and ring knife edge 21 or 27. The thread portion still held by the needle will be interknit in the stocking when the needle is retracted and the other end of the severed thread will be held by the shoe so that it cannot become entangled in the continuing knitting process. As the ring knife continues to rotate, cam 24 will engage shoe 25 to raise it and thereby release the cut thread end, whereupon such thread end will be pulled by suction into underlying registry with tube 37. The free ends of threads F2 and F4 will thus be held out of the path of needles 18 until reinforcing thread is again required for a subsequent portion of the knitting cycle.

The vibrating counterknife provides positive cutting or shearing action so that the thread is cut at a particular location and assures that each thread fed to it will be cut accurately rather than slipping past the counterknife without being cut cleanly or being torn apart by tension at an undetermined location as has been the case in previous cutting devices. Because the ring knife and its rib 22 rotate in synchronism with the needle cylinder, the rib will be in the same rotative position for each cutting operation so that the serrated surface 23 can be restricted to a short arc along the rib periphery. FIG. 2 shows a cam surface of less than half of the circumferential extent of the rib. Consequently, wear of the bellcrank 13 and the counterknife will be reduced by limiting vibratory motion of the knife to the time when the thread stretch is to be cut.

To prevent counterknife 11 from swinging into the path of needles 18, an adjustable stop 10 on bracket 9 is engageable by the arm of bellcrank 13 remote from the counterknife to limit inward movement of such arm and, consequently, outward movement of the counterknife is limited. The effective depth of the grooves in the serrated surface can thus be regulated.

Instead of the bellcrank holder 13 and serrated cam surface 23, a planar counterknife holder could be used, such as shown in FIG. 5, in which cam follower 130 engages eccentric 26 rotatable on a vertical shaft 41 of a motor 40 to effect vibration of the counterknife. Such motor is shown to be mounted by two angle brackets 42 and 43 on machine frame 44. A leg of lower bracket 43, which extends across the needle gap between the frame 44 and holder 13, provides a bearing for motor shaft 41. Alternatively, cam 26 could be driven through suitable gearing by shaft 4 of the rotary disk 1.

In FIGS. 6, 7 and 8 a somewhat different counterknife mounting and vibrating mechanism is shown. In this instance, the interacting surfaces of the ring knife 2 and counterknife are inclined rather than horizontal. The knife is mounted in a holder 132, which holder is reciprocable through a bearing sleeve 90 on cover plate 6. The path of reciprocation is parallel to the incline of the engageable knife surfaces. The serrated cam surface 23 in this instance is radially inward from the cutting edge 21 of ring knife 2. Cam follower 133 depending from knife holder 132 is radially inward of the cam surface. Consequently, tension spring 8 connected between mounting sleeve 90 and the end of holder 132 remote from the counterknife biases holder 132 toward the lower right of FIG. 6 to maintain the cam follower in engagement with its cam surface.

In order to minimize the vibration amplitude while preventing the thread from slipping away from the counterknife, such counterknife could be sickle-shaped, or at least its radially inward thread-engaging edge could be concave. Such minimization of amplitude is desireable to prevent the counterknife from extending into the path of needles 18. With the construction of FIGS. 6, 7 and 8, the counterknife moves only in a radial plane of the ring knife so that its angle relative to ring knife 2is constant.

As previously discussed, it is desirable to tension the thread extending across the ring knife cutting edge to facilitate its cutting and, in the construction of FIG. 2, such tension was provided by a shoe 25 cooperating with rib 22. In FIGS. 3 and 4 an alternative tensioning mechanism is shown including a disc 50 mounted by a bolt 51 to suction tube 37. The disk 50 rolls on rib 22 by frictional engagement therewith and is held in such engagement by its own weight. The outer disk is rigid and resilient means bias the lower portion of the inner disk radially outward and thereby hold it in engagement with rib 22. The disk 50, therefore, is rotatable about horizontal bolt 51. Such rotation may be effected simply by frictional engagement between the lower portion of the disk and rib 22 rotating about a vertical axis.

As the thread to be cut is pulled across rib 22 by needle 18, it will be drawn between the engageable faces of the rib and disk 50 to tension such thread. After the thread has been cut, continued rotation of disk 50 will release the thread end which will be drawn by suction into tube 37. The aperture in such disk receiving bolt 51 should be somewhat larger than the bolt to provide sufficient play to permit entry of the thread between such disk and rib 22. The disk 50 and the rib 22 preferably have complemental interengaging profiles whereby the disk 50 may have a circumferential groove 52 to embrace rib 22 as a track, as shown in FIGS. 3 and 4.

As has been mentioned previously, it is desirable to cut reinforcing threads quite close to needles 18. However, during exchange of threads of different denier, such as between the welt and the body of a stocking, the cut thread end should be somewhat longer to provide sufficient welt thread to be drawn into the stocking to prevent a faulty body-welt junction. Consequently, it is necessary to provide mechanism for changing the distance between the ring formed by needles l8 and the cutting location of knives 2 and 11. Suitable mechanism for this purpose is shown in FIG. 1.

Such change in distance between the needles and the cutting mechanism can be effected by raising and lowering the disk 1, cover plate 6 and the cutting and tensioning mechanism supported on them. Shaft 4 rotatively supporting disk 1 is encased in a nonrotative sleeve 30, to which sleeve is fastened collar 60 of cover plate 6. The upper end of sleeve 30 is secured in a ring 32 having a lower stepped side, the offset portions of which are joined by a circumferentially inclined portion. A shifting ring 34 beneath ring 32 has an upper stepped side complemental to and engageable with the stepped lower side of ring 32 and also has a circumferentially inclined portion. A mounting arm 31 projects from the knitting machine frame and guides sleeve 30 for axial movement therein. The upper surface of mounting arm 31 supports the lower planar side of ring 34.

A helical compression spring 33 biases sleeve 30 downward to urge the stepped sides of rings 32 and 34 into engagement.

In the position of FIG. 1, the thick portion of ring 34 is in underlying registry with the thin portion of ring 32; and disk 1 and cover plate 6 are in their lower positions, whereby the cutting mechanism is closest to needles 18 as required for cutting reinforcing threads.

To raise the disk assembly 1, 6 into a position suitable for cutting threads after a change of denier, a Bowden wire 35 connected to an arm on shifting ring 34 is actuated to turn such ring about its axis. A post 62 on cover plate 6 extends into a bore in an ear of mounting am 31 to prevent rotation of cover plate 6 and its collar 60 and thereby to prevent rotation of sleeve 30 and ring 32. Because this ring cannot rotate relative to mounting arm 31, the inclined portions of the stepped faces of rings 32 and 34 cooperate to wedge ring 32 upward. Such upward movement is transmitted through ball bearing 36 to drive wheel 45 keyed to shaft 4 so that such shaft and disk 1 are conjointly raised. When shifting ring 34 is turned back to the position of FIG. 1, gravity and spring 33 will effect conjoint downward movement of ring 32 and the entire assembly supported by sleeve 30.

When threads of different denier are exchanged, the'threadcutting operation can be effected without the counterknife being vibrated. Such thread can be cut simply by being drawn between knives 2 and 11 as needle 18 carrying such thread advances relative to the counterknife as indicated at the lower right of FIG. 2. The counterknife arrangement in FIG. 6 is particularly suitable for selectively utilizing the vibratory motion. When no vibration is desired, the counterknife holder 132 can simply be drawn to the left of that figure by Bowden wire 134 until cam surface 23 and cam follower 133 are disengaged. It will be seen that the interacting knife surfaces have sufficient width along the incline to remain in cutting engagement even though the counterknife is moved sufficiently to disengage the cam follower.

The vibration of counterknife 11 can be arrested by the mechanism shown in FIG. 5. Such vibration-arresting device can be used to disengage cam follower from cam surface 23 in FIG. 2 or from eccentric 26 in FIG. 5. The holder 13 has an upstanding arm 131 on its end remote from counterknife 11. The upper edge of arm 131 is beveled and engages the oppositely beveled end of an arm 46 supported on machine frame 44. As the counterknife holder is raised by the shifting ring 34 of FIG. 1, the cooperating bevels of arms 46 and 131 wedge the cam-follower end of holder 13 outward so that cam follower 130 is disengaged from cam disk 26 or cam surface 23. When the counterknife holder 13 is again lowered, spring 8 will bias the cam follower into engagement with its cam 23 or 26.

When it is necessary from time to time to replace a worn counterknife blade 11, the holder 13 can be pulled upward by a Bowden wire 38, for example, as shown in FIGS. 1, 2 and 3. In this manner such replacement could be made without disassembling the knitting machine and, if desired, without shutting down the machine.

We claim:

1. Thread-cutting mechanism for circular knitting machines including a rotatable ring of needles, liftable guides for thread fed to the needles, a disk carrying sinkers and being rotated in synchronism with the ring of needles, and a stationarily mounted cover plate for the disk, wherein the improvement comprises a ring knife concentrically supported by the cover plate, said ring knife being rotatable in synchronism with the disk and having annular rib means on the ring knife upper surface near its outer margin, vibrating means including a plurality of cam means carried on a lateral face of said rib means, a nonrotatable counterknife biased for engagement with said ring knife, holder means for said counterknife, and a cam follower supported from said holder means, said follower being biased against said cam means to transfer a vibrating movement to said counterknife.

2. The cutting mechanism defined in claim 1, in which the cam means are serrations only along an are less than the full circumference of the rib lateral face.

3. The cutting mechanism defined in claim 1, in which the ring knife has a substantially horizontal cutting edge, and pivot means mounting the counterknife holder means for vibration about an upright axis, the cam follower on the holder means being spaced from said pivot means transversely of such upright axis.

4. The cutting mechanism defined in claim 1, in which the counterknife holder means is mounted for reciprocation along a line in a substantially radial plane of the sinker-carrying disk.

5. The cutting mechanism defined in claim 1, in which the ring knife has a smooth cutting edge.

6. The cutting mechanism defined in claim l, in which the counterknife has a concave cutting edge.

7. The cutting mechanism defined in claim 1, and means to shift the counterknife holder means for disengaging the cam follower from the cam means.

8. The cutting mechanism defined in claim 1, and shifting means operable to shift the ring knife and counterknife equidistantly relative to the needle ring.

9. The cutting mechanism defined in claim 8, and means for disengaging the cam follower from the cam means by shifting of the ring knife and counterknife away from the needle ring.

10. The cutting mechanism defined in claim 1, in which the rib means includes an upstanding annular rib on the ring knife, and thread-tensioning means for tensioning a thread extending across the ring knife including thread-restraining disk means having a bore therein and rotatable about an axis extending transversely of the axis of rotation of the ring knife and bolt means smaller than and extending through such bore for supporting said disk means to roll yieldingly on said upstanding annular rib.

Ill. The cutting mechanism defined in claim 10, in which the disk means and the annular :rib have interengaging profiles.

l2. Thread-cutting mechanism for circular knitting machines including a rotatable ring of needles, liftable guides for thread fed to the needles, a disk carrying sinkers and being rotated in synchronism with the ring of needles, and a stationarily mounted cover plate for the disk, wherein the improvement comprises cutting means supported by the cover plate and having a cutting edge, rib means including an upstanding annular rib carried by the cutting means, and threadtensioning means for tensioning a thread extending across said cutting edge and including thread-restraining disk means having a bore therein and rotatable about an axis extending transversely of the axis of rotation of the sinker-carrying disk and bolt means smaller than and extending through such bore for supporting said disk means to roll yieldingly on said upstanding annular rib.

3 3 WWW STATES PATENT @Wmm @ERHMGME @F RRECTWW Patent No. 3 648 485 Damd M M 1,4 0 197;

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1. Thread-cutting mechanism for circular knitting machines including a rotatable ring of needles, liftable guides for thread fed to the needles, a disk carrying sinkers and being rotated in synchronism with the ring of needles, and a stationarily mounted cover plate for the disk, wherein the improvement comprises a ring knife concentrically supported by the cover plate, said ring knife being rotatable in synchronism with the disk and having annular rib means on the ring knife upper surface near its outer margin, vibrating means including a plurality of cam means carried on a lateral face of said rib means, a nonrotatable counterknife biased for engagement with said ring knife, holder means for said counterknife, and a cam follower supported from said holder means, said follower being biased against said cam means to transfer a vibrating movement to said counterknife.
 2. The cutting mechanism defined in claim 1, in which the cam means are serrations only along an arc less than the full circumference of the rib lateral face.
 3. The cutting mechanism defined in claim 1, in which the ring knife has a substantially horizontal cutting edge, and pivot means mounting the counterknife holder means for vibration about an upright axis, the cam follower on the holder means being spaced from said pivot means transversely of such upright axis.
 4. The cutting mechanism defined in claim 1, in which the counterknife holder means is mounted for reciprocation along a line in a substantially radial plane of the sinker-carrying disk.
 5. The cutting mechanism defined in claim 1, in which the ring knife has a smooth cutting edge.
 6. The cutting mechanism defined in claim 1, in which the counterknife has a concave cutting edge.
 7. The cutting mechanism defined in claim 1, and means to shift the counterknife holder means for disengaging the cam follower from the cam means.
 8. The cutting mechanism defined in claim 1, and shifting means operable to shift the ring knife and counterknife equidistantly relative to the needle ring.
 9. The cutting mechanism defined in claim 8, and means for disengaging the cam follower from the cam means by shifting of the ring knife and counterknife away from the needle ring.
 10. The cutting mechanism defined in claim 1, in which the rib means includes an upstanding annular rib on the ring knife, and thread-tensioning means for tensioning a thread extending across the ring knife including thread-restraining disk means having a bore therein and rotatable about an axis extending transversely of the axis of rotation of the ring knife and bolt means smaller than and extending through such bore for supporting said disk means to roll yieldingly on said upstanding annular rib.
 11. The cutting mechanism defined in claim 10, in which the disk means and the annular rib have interengaging profiles.
 12. Thread-cutting mechanism for circular knitting machines including a rotatable ring of needles, liftable guides for thread fed to the needles, a disk carrying sinkers and being rotated in synchronism with the ring of needles, and a stationarily mounted cover plate for the disk, wherein the improvement comprises cutting means supported by the cover plate and having a cutting edge, rib means including an upstanding annular rib caRried by the cutting means, and thread-tensioning means for tensioning a thread extending across said cutting edge and including thread-restraining disk means having a bore therein and rotatable about an axis extending transversely of the axis of rotation of the sinker-carrying disk and bolt means smaller than and extending through such bore for supporting said disk means to roll yieldingly on said upstanding annular rib. 